Central venous dialysis catheter dysfunction

Central venous catheter dysfunction is a limiting factor in regard to renal replacement therapy efficiency and can thus influence patient morbidity. Early catheter dysfunction is frequently due to mechanical problems such as inadequate positioning, kinking, or constriction, but early fibrin deposition can develop soon after insertion. Delayed dysfunction usually results from thrombus formation, either within the lumen, around the catheter ("fibrin sleeve"), or in the host vein. Catheter dysfunction is suspected clinically or documented by simple imaging studies. It is usually evident and manifested by failure to aspirate blood from the lumen(s), inadequate blood flow and/or high resistance pressures during hemodialysis. However, a more subtle dysfunction may lead to a high recirculation of dialyzed blood and be overlooked if dialysis adequacy is not monitored regularly. Local instillation of a fibrinolytic agent is usually successful in restoring catheter patency. Central venous dialysis catheters present intrinsic limitations consequent to their composition and design, whereas extrinsic limitations result from site of insertion, blood properties and anatomic particularities of a given individual. These characteristics largely determine overall catheter performances. Performance parameters to consider include maximal consistently achievable blood flow rate, resistance to blood flow indicated by arterial and venous pressures during hemodialysis, and blood recirculation rate. Catheter longevity is an important consideration for cuffed catheters implanted for long-term use. The tolerated blood recirculation within central venous dialysis catheters should be below 10% to 15%, and is ideally between 3% to 7% in most clinical settings. Several recent studies confirm that short femoral catheters recirculate significantly more than is desirable. Well functioning and nonreversed internal jugular and subclavian venous catheters have, in general, recirculation rates less than 5%. With regard to various performance criteria, the TwinCath (Medcomp, Harleysville, PA) appears particularly advantageous. In any case, a good catheter maintenance program is of critical importance for the prevention and the early detection of catheter dysfunction.